Art with white background – Photography Stack Exchange

I am working on photography art work (from my wife) which has a white background and elements which are white with no paint. I have a reasonably good Nikon D3400, tripod, lighting with 4 5000K lights (LED 1600 lumens). The background comes out with a bit of grey in it, which I can rip out using photoshop magic brush. The problem is that it’s hard to rip out the white within the painted object, oh like a zebra swallowtail butterfly, as there are lines in the art which are greyish too.

I’ve been trying to follow directions on lighting etc. Adjusting the lightness on the camera, adjusting the color in Luminar and/or Photoshop. Using a Passport Colorchecker, bringing in the color profile to Luminar (which is like photoshop, I just didn’t want to buy a newer photoshop than CS2) and adjusting.
The printer is a Canon Pro-100.

Nothing is giving satisfaction. I’ll include an image (at a lower res) so you can see. So, I am wondering what pros do when photographing art like this (acrylic painting) for reproduction by printing.

Zebra Swallowtail